The present invention is directed to a method of identifying, or labelling, cooperating parts after the cooperating parts have been disassembled from each other for purposes of repair, or for general disassembly of parts. The present invention has especial relevance to the repair of automotive engines, during which many parts may be disassembled and mixed up, thereby causing a mechanic to forgot which part is associated with which other part. The invention may be used in other areas as well, such as electrical repair, where parts are also disassembled and ofttimes mixed up, which also may require much time and effort on the part of the repairman, in order to find the right, mating part for a component when reassembly is performed after the repair. Any field in which cooperating parts must be assembled, such as do-it-yourself kits, or the like, where the parts are put together for the first time by the owner, may use the invention in order to identify cooperating, or mating, parts, or components, for subsequent assembly or re-assembly.